1. Field of the Invention
The present invention relates to microjoint separation apparatus for separating a product which has been processed with a microjoint. In one aspect the invention relates to a separation apparatus for separating a product which has been processed with a microjoint and then subjected to a tapping process.
2. Description of the Related Art
A microjoint is a weakened line of severance in a workpiece which is suitable for temporarily holding a product within the frame of the workpiece during the fabrication of the product, while subsequently permitting an easy separation of the product from the frame. A microjoint can have any suitable form, e.g. a continuous line of substantially reduced thickness in comparison to the remainder of the workpiece thickness or a line of complete separation interrupted by occasional strips of joinder. Such joinder strips can be in any suitable form, e.g. flat strips, threads, wires, etc., and can have a thickness which is the same as or less than the thickness of the workpiece frame.
A method of producing a large number of individual products from a plate-like workpiece using a sheet metal working machine, e.g. a turret punch press or a laser beam machine, has been known in which the working is performed in the state where the workpiece and a product contained therein are connected by a microjoint. After such working, the product is separated from the remainder of the workpiece at the microjoint or wire joint. Further, when tapping is to be performed on a product which has been produced by microjoint processing, a tapping device can be provided on the sheet metal working machine to perform such tapping after the microjoint processing and before the separation.
However, when such tapping device is provided, a large difference results between the cycle time necessary for the tapping operation after such microjoint processing and the cycle time necessary for a microjoint separation apparatus to separate the product from the remainder of the workpiece at the microjoint. If a system is constructed by setting a microjoint separation apparatus on the downstream side of the sheet metal working apparatus, a problem occurs in that productivity is greatly reduced as the line balancing is worsened.
Apparatus for separating a product processed with microjoints from the remainder of the workpiece has been known, e.g. the apparatus disclosed in Japanese Utility Model Laid-Open Publication No. 61-159121. Such an apparatus is provided with a plurality of rotating hammers, and the workpiece is struck by these hammers in the vicinity of the microjoint in order to separate the product from the remainder of the workpiece.
However, the hammers in such separating apparatus may not accurately strike the vicinity of a microjoint, depending on the type of product to be processed, resulting in a problem that the apparatus is susceptible to an error in the separation process.
In one conventional method a punch, used exclusively for the purpose of separating a microjoint, is provided within a sheet metal working machine in order to separate the microjoint immediately after the completion of the working of the product. In another conventional method a punch and die unit, for separating along a microjoint, is provided above a workpiece holding table, with the punch and die unit travelling in the transverse direction of the workpiece; and the separating position is determined by moving the workpiece in the direction orthogonal to the punch and die unit.
However, the method of providing a punch, exclusively for separation, within the sheet metal working apparatus is not easy to be implemented because it requires a large modification of a machine body. Further, there is also a problem in that the apparatus as a whole becomes expensive. For example, a large scale sending-out or delivery device can be required in order to discriminate between the workpiece frame and the product, due to the fact that the frame and the separated product remain on the same worktable.
On the other hand, the punch and die unit method causes a problem in that it requires a large space for the installation of the punch and die unit, and the apparatus as a whole becomes expensive since a worktable must be provided exclusively for the separation of the microjoint.